which is a second order Fuchsian equation with 4 singular points.
The DCHE is obtained by a coalescence of the regular singularities
\(x=a,\,x=\infty \)  and \(x=0, x=1\)  of the GHE. The first confluent procedure leads to the irregular singularity
at \(x=\infty \)  while the second leads to the irregular singularity \(x=0\)  of the DCHE (see [1]}).
The double confluent Heun equation finds many applications in superconductivity [2]},
statistical mechanics [3]}, gravity [4]}.
